The 2015 FIA Formula One World Championship was a motor racing championship for Formula One cars. It was the 66th Formula One World Championship recognised by the sport's governing body, the Fédération Internationale de l'Automobile (FIA), as the highest class of competition for open-wheel racing cars. Twenty-two drivers representing 10 teams contested 19 Grands Prix, starting in Australia on 15 March and ending in Abu Dhabi on 29 November as they competed for the World Drivers' and World Constructors' championships.

Lewis Hamilton was the defending Drivers' Champion after securing his second title at the 2014 Abu Dhabi Grand Prix. His team, Mercedes, began the season as the defending Constructors' Champion, having clinched its first championship title at the 2014 Russian Grand Prix.

The calendar featured two significant changes from the 2014 season. The first was the return of the Mexican Grand Prix, held for the first time since 1992. The other change was the cancellation of the German Grand Prix after a venue could not be agreed upon, leaving the nation without a World Championship event for the first time in fifty-five years.

Hamilton secured his third Drivers' Championship with three races left in the season. The runner-up was his teammate Nico Rosberg, 59 points behind, with Ferrari's Sebastian Vettel third, another 44 points adrift. Mercedes AMG Petronas F1 Team clinched the 2015 Constructors' Championship at the Russian Grand Prix, ahead of Ferrari and Williams, and ended the season with a record 703 points. Hamilton also won the FIA Pole Trophy with a total of 11 pole positions in the season and the DHL Fastest Lap Award. Ferrari won the inaugural DHL Fastest Pit Stop Award. This season was also the first in which future World Champion Max Verstappen competed.

The following teams and drivers took part in the 2015 Formula One World Championship. All teams competed with tyres supplied by Pirelli.

Four drivers drove as third or test drivers throughout the season.

Several team changes took place before the season began. Both McLaren and Lotus changed engine suppliers for the 2015 season. McLaren ended their 20-year partnership with Mercedes-Benz, in favour of a return to full-works Honda, who had previously supplied them from 1988 until 1992. Honda had been absent for seven years: they had provided British American Racing and Jordan Grand Prix with engines until they purchased the former in 2006 and then had competed as a constructor until 2008 and thus a Japanese-licensed engine manufacturer returned to the sport for the first season since 2009 when Toyota was the last Japanese-licensed engine manufacturer to compete.

Lotus ended its association with Renault in favour of a deal with Mercedes. This ended a 20-year involvement of Renault with the Enstone-based team, (which operated as Benetton from 1992 until 2001, as Renault from 2002 until 2011 and as Lotus from 2012 until 2015) after being an engine supplier to Benetton since 1995, and being the owner of the team from 2002 to 2010.